package com.yinsin.jpabatis.io;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.net.URLConnection;
import java.nio.charset.Charset;
import java.util.Properties;

public class Resources {
	private static ClassLoaderWrapper classLoaderWrapper = new ClassLoaderWrapper();

	/**
	 * Charset to use when calling getResourceAsReader. null means use the
	 * system default.
	 */
	private static Charset charset;

	Resources() {
	}

	/**
	 * Returns the default classloader (may be null).
	 *
	 * @return The default classloader
	 */
	public static ClassLoader getDefaultClassLoader() {
		return classLoaderWrapper.defaultClassLoader;
	}

	/**
	 * Sets the default classloader
	 *
	 * @param defaultClassLoader
	 *            - the new default ClassLoader
	 */
	public static void setDefaultClassLoader(ClassLoader defaultClassLoader) {
		classLoaderWrapper.defaultClassLoader = defaultClassLoader;
	}

	/**
	 * Returns the URL of the resource on the classpath
	 *
	 * @param resource
	 *            The resource to find
	 * @return The resource
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static URL getResourceURL(String resource) throws IOException {
		// issue #625
		return getResourceURL(null, resource);
	}

	/**
	 * Returns the URL of the resource on the classpath
	 *
	 * @param loader
	 *            The classloader used to fetch the resource
	 * @param resource
	 *            The resource to find
	 * @return The resource
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static URL getResourceURL(ClassLoader loader, String resource) throws IOException {
		URL url = classLoaderWrapper.getResourceAsURL(resource, loader);
		if (url == null) {
			throw new IOException("Could not find resource " + resource);
		}
		return url;
	}

	/**
	 * Returns a resource on the classpath as a Stream object
	 *
	 * @param resource
	 *            The resource to find
	 * @return The resource
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static InputStream getResourceAsStream(String resource) throws IOException {
		return getResourceAsStream(null, resource);
	}

	/**
	 * Returns a resource on the classpath as a Stream object
	 *
	 * @param loader
	 *            The classloader used to fetch the resource
	 * @param resource
	 *            The resource to find
	 * @return The resource
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static InputStream getResourceAsStream(ClassLoader loader, String resource) throws IOException {
		InputStream in = classLoaderWrapper.getResourceAsStream(resource, loader);
		if (in == null) {
			throw new IOException("Could not find resource " + resource);
		}
		return in;
	}

	/**
	 * Returns a resource on the classpath as a Properties object
	 *
	 * @param resource
	 *            The resource to find
	 * @return The resource
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static Properties getResourceAsProperties(String resource) throws IOException {
		Properties props = new Properties();
		try (InputStream in = getResourceAsStream(resource)) {
			props.load(in);
		}
		return props;
	}

	/**
	 * Returns a resource on the classpath as a Properties object
	 *
	 * @param loader
	 *            The classloader used to fetch the resource
	 * @param resource
	 *            The resource to find
	 * @return The resource
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static Properties getResourceAsProperties(ClassLoader loader, String resource) throws IOException {
		Properties props = new Properties();
		try (InputStream in = getResourceAsStream(loader, resource)) {
			props.load(in);
		}
		return props;
	}

	/**
	 * Returns a resource on the classpath as a Reader object
	 *
	 * @param resource
	 *            The resource to find
	 * @return The resource
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static Reader getResourceAsReader(String resource) throws IOException {
		Reader reader;
		if (charset == null) {
			reader = new InputStreamReader(getResourceAsStream(resource));
		} else {
			reader = new InputStreamReader(getResourceAsStream(resource), charset);
		}
		return reader;
	}

	/**
	 * Returns a resource on the classpath as a Reader object
	 *
	 * @param loader
	 *            The classloader used to fetch the resource
	 * @param resource
	 *            The resource to find
	 * @return The resource
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static Reader getResourceAsReader(ClassLoader loader, String resource) throws IOException {
		Reader reader;
		if (charset == null) {
			reader = new InputStreamReader(getResourceAsStream(loader, resource));
		} else {
			reader = new InputStreamReader(getResourceAsStream(loader, resource), charset);
		}
		return reader;
	}

	/**
	 * Returns a resource on the classpath as a File object
	 *
	 * @param resource
	 *            The resource to find
	 * @return The resource
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static File getResourceAsFile(String resource) throws IOException {
		return new File(getResourceURL(resource).getFile());
	}

	/**
	 * Returns a resource on the classpath as a File object
	 *
	 * @param loader
	 *            - the classloader used to fetch the resource
	 * @param resource
	 *            - the resource to find
	 * @return The resource
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static File getResourceAsFile(ClassLoader loader, String resource) throws IOException {
		return new File(getResourceURL(loader, resource).getFile());
	}

	/**
	 * Gets a URL as an input stream
	 *
	 * @param urlString
	 *            - the URL to get
	 * @return An input stream with the data from the URL
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static InputStream getUrlAsStream(String urlString) throws IOException {
		URL url = new URL(urlString);
		URLConnection conn = url.openConnection();
		return conn.getInputStream();
	}

	/**
	 * Gets a URL as a Reader
	 *
	 * @param urlString
	 *            - the URL to get
	 * @return A Reader with the data from the URL
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static Reader getUrlAsReader(String urlString) throws IOException {
		Reader reader;
		if (charset == null) {
			reader = new InputStreamReader(getUrlAsStream(urlString));
		} else {
			reader = new InputStreamReader(getUrlAsStream(urlString), charset);
		}
		return reader;
	}

	/**
	 * Gets a URL as a Properties object
	 *
	 * @param urlString
	 *            - the URL to get
	 * @return A Properties object with the data from the URL
	 * @throws java.io.IOException
	 *             If the resource cannot be found or read
	 */
	public static Properties getUrlAsProperties(String urlString) throws IOException {
		Properties props = new Properties();
		try (InputStream in = getUrlAsStream(urlString)) {
			props.load(in);
		}
		return props;
	}

	/**
	 * Loads a class
	 *
	 * @param className
	 *            - the class to fetch
	 * @return The loaded class
	 * @throws ClassNotFoundException
	 *             If the class cannot be found (duh!)
	 */
	public static Class<?> classForName(String className) throws ClassNotFoundException {
		return classLoaderWrapper.classForName(className);
	}

	public static Charset getCharset() {
		return charset;
	}

	public static void setCharset(Charset charset) {
		Resources.charset = charset;
	}
}
